The present invention relates to a hand-guided working tool, especially a trimmer, a motor chainsaw, a cutter etc., comprising an internal combustion engine with a cylinder and a crankcase enclosed in a housing, wherein a crankshaft that drives a tool and a blower is provided, the blower arranged in a blower chamber and taking in cooling air through a cooling air inlet to be supplied to the internal combustion engine, wherein the blower has furthermore at least one combustion air inlet for taking in combustion air that is guided via a combustion air outlet through a combustion air channel to an air filter box.
From German Patent 37 08 289 a motor chainsaw is known having a housing with an air-cooled combustion engine. On one end of the crankshaft of the combustion engine a drive member (chain-driving pinion) for a tool is provided, i.e., a saw chain guided within a guide rail. The other end of the crankshaft supports a blower wheel that is embodied as a fly wheel for providing the required cooling air flow to the cylinder of the internal combustion engine. The blower wheel conveys at the same time combustion air to the air filter box of the internal combustion engine whereby air guiding vanes are provided which separate the combustion air intake from the cooling air intake for providing a separate intake path of cooling air and combustion air. With this arrangement, combustion air is to be supplied to the engine from a less contaminated area. The required expenditure, however, is very high and cannot ensure that a sufficient separation of the combustion air flow from the cooling air flow is provided. The air guiding vanes increase the axial constructive length substantially and impede furthermore the formation of the cooling air flow.
It is therefore an object of the present invention to improve a working tool of the aforementioned kind such that for a minimal constructive space and with simple constructive means a sufficient cooling air flow and a clean combustion air flow are provided.